Mobile communication devices, such as cellular telephones, personal digital assistants, mobile personal computer terminals, etc., have become widely used as advancements have been made in mobile communication systems. Mobile communication systems may be capable of transmitting/receiving signals in various frequency bands, such as 800 MHz to 1.0 GHz, 1.5 GHz to 2.0 GHz, etc.
Components of mobile communication equipment must be miniaturized and have enhanced performance characteristics. Demand for reducing the size and manufacturing costs of mobile communication equipment is ever increasing. Additionally, studies for reducing the size and manufacturing costs of the components have been actively conducted
An RF transceiver supports multiple bands (multi-bands) and multiple modes (multi-modes), and recent RF transceivers require a form factor having a smaller size due to the miniaturization of mobile communication equipment, such as cellular telephones. However, supporting multi-bands and multi-modes in smaller mobile communication equipment is very difficult. The conventional approach is to integrate available receiver or transceiver ICs for Bluetooth, GPS, Cellular band transceiver, WiFi, etc. . . . , which is not an ideal approach to minimize cost and circuit area.
It would therefore be desirable to provide a quadrature bandpass-sampling technique that makes it possible to down-convert and digitize RF signals in excess amount of signal bandwidth. In such a system, several RF signals in various frequency bands would be frequency-shifted to form a cluster of signals at a high intermediate frequency, wherein demodulation and digitization can be applied to simultaneously down-convert all RF signals of interest to a second low intermediate frequency. A second digital down-conversion can be then applied on all the frequency-shifted RF signals to achieve simultaneous demodulation to baseband.